Influenza A (H1N1) Outbreak (2009)  

"Looking ahead in the weeks and months ahead, especially for countries in the northern hemisphere, when they will be going into the winter, we need to maintain our vigilance and see how the disease will evolve."

Margaret Chan, Chief of the World Health Organization told reporters on a visit to Tanzania.

Source: The China Daily, 17 Aug 2009

How the H1N1 virus got its start

The 2009 Influenza A(H1N1) flu outbreak, popularly known as "swine flu", is due to a new strain of flu virus that has infected 1893 people in 23 countries and killed 29 people in Mexico and 2 person in the United States as at 6 May 2009 according to World Health Organization (WHO). There is widespread concern that this outbreak may lead to a devastating global health problem on a scale comparable to the 1918 Spanish influenza pandemic that infected more than 500 million people worldwide. The current Influenza A(H1N1) is a sub-variant type that developed from viruses that infected swine, hence its initial name, the “swine virus”.

The outbreak began in Mexico and was officially reported in April 2009. However, Mexico was already in the midst of an epidemic for months before the outbreak was recognized. An extensive network of international monitoring systems was swiftly established in preparation for the outbreak after the World Health Organization, WHO declared the Influenza A(H1N1) infection a public health emergency. Information-gathering efforts and monitoring regimes were stepped up. This is because humans are not normally susceptible to swine flu and in the rare instance they are infected, their symptoms are usually mild. Abnormal situation has emerged in Mexico as a new virulent strain of H1N1 virus of swine origin was detected.

Mexico's government imposed shutdown of the metropolis where the outbreak sickened the most people to curb the flu's spread. Soon the flu sickness spreads beyond Mexico, the epicenter of infections to North America, Europe and Asia. On 30 April, WHO raised its influenza pandemic alert to phase 5 indicating that a full pandemic is imminent. Singapore has correspondingly raised its alert level to Orange (indication of the situation when virus evolves into human disease).

The date and location of the first H1N1 flu outbreak is still unknown. The United States Centers for Disease Control and Prevention (CDC) first isolated the new strain of virus in two Southern Californian children who had been ill since late March and posted an early alert on its Morbidity and Mortality Weekly Report website on 21 April. The posting alerted the Mexican authority, as there was a surge in influenza-like illnesses experienced in March and early April in several areas of the country and this raised the possibility that these cases were the result of the influenza A(H1N1) virus infection.

A five-year-old Mexican boy, Edgar Hernandez, was dubbed as "patient zero" and he could have been Mexico’s earliest confirmed case of the H1N1 flu. Edgar's case gained attention because he lives near a large pig farm, fueling suspicion that the outbreak could have started there. However, the lack of contact between the two Californian children, as well as a lack of contact with swine, suggests that the virus spreads from human to human. Although all three children recovered, the likelihood that this H1N1 virus can be humanly transmitted is a cause for concern.

The early days of outbreak in Asia

On 1 May, Hong Kong reported Asia’s first H1N1 case after a Mexican tourist who arrived there via Shanghai was tested positive. The health authority declared a public emergency. Hundreds of hotel guests and workers were quarantined at the Metropark hotel where he had stayed. With memories of 2003's deadly SARS outbreak still fresh, the Hong Kong government took tough measures to contain the potential spread of the disease, by urging residents not to travel to Mexico and to immediately detain at the hospital anyone who arrived with fever and flu-like symptoms after traveling to countries with confirmed outbreaks.

The next day, South Korea reported that a woman who had recently visited Mexico was tested positive for H1N1 virus and raised its alert status. The South Korean authority issued travel warnings about Mexico, tightened checks on inbound travelers and boosted inspections of pork products. Several days later, the South Korean Health Ministry confirmed the first case of a human-to-human infection in Asia. The patient was in contact with the first case that was tested positive for the H1N1 virus.

China suspended direct flights from Mexico to Shanghai on concern that travelers may transmit the flu virus. Health authorities in China’s southern Guangdong province also sought to contact passengers on the same flight as the Mexican patient in Hong Kong. Its emergency measures infuriated the Mexican government and led to a major diplomatic row between the two nations.

A week after the world braced for the arrival of the deadly flu, Mexico authority cited improvement in the battle against the H1N1 virus. A wide-ranging shutdown of Mexico City including government offices, restaurants, museums and churches reopened on 7 May, in an effort to revive the devastated tourism sector. However, officials at WHO has cautioned nations not to let their guards down, as the disease is probably not going to slow down any time soon and there may be a second and more severe wave of infection.

Swine flu goes global

Worldwide, the H1N1 virus infection continued to spread with increase in the number of confirmed H1N1 cases and deaths. A full list of countries with confirmed cases is on the WHO Web site.  As of 23 August, WHO reported an international situation: over 209,438 laboratory-confirmed cases of 2009 H1N1 influenza virus with at least 2,185 deaths. The 2009 H1N1 influenza virus continues to be the dominant influenza virus in circulation in the world.

Influenza A (H1N1) vaccines

On 1 May, scientists at the CDC reported some good news. “All of the genes of all the viruses we’ve examined are 99 to 100 percent identical." says Nancy Cox, chief of the influenza division at the CDC. “This means it will be somewhat easier to produce an influenza vaccine." Six to seven million doses of the H1N1 vaccine are available from the first week of October. The vaccine should be effective against the virus within eight days.

Some antiviral flu drugs such as Tamiflu and Relenza have been shown to help people who are infected, as long as they take the medicine within two days of when symptoms first appeared.